How do I modify existing tables?
There are several ways:
tail +2 < table2 >> table1
addrow < table | compute 'if($0 ~ /^\t+$/) Column1="value1"; Column2="value2"; ...' \ > table.tmp mv table.tmp table
getrow 'selection expression' < table > table.tmp mv table.tmp table
Will NoSQL ever provide record-level locking and update facilities?
NoSQL assumes that tables are collections of variable-length records. Strictly speaking, record-level updates require fixed-length records. They can be done by right-padding the records with blanks to 'make room' for updates, but that is a bit of a kludge, IMHO. If you need such facilities you should use either /rdb or Starbase, or resort to a more usual SQL DBMS, either free or commercial. See also the workaround outlined in page Big tables. In fact I am thinking of a mechanism to provide some form of record-level facilities, but in a way that is in accordance with the underlying paradigm of variable-length records.